Unidirectional dynamic interbody fusion device and method of use

ABSTRACT

An interbody fusion device includes a top member, a base member, and an expansion member. The top member includes a first bone-engaging side and a threaded opening. The base member is received by the top member and includes a second bone-engaging side and an open cavity aligned with the threaded opening of the top member. The expansion member is disposed within the open cavity for rotation about an axis. The expansion member includes a threaded portion threadably engaged with the threaded opening. Rotation of the expansion member translates the first bone-engaging side away from the second bone-engaging side along the axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/753,503 filed on Jun. 29, 2015, (U.S. Pat. No. 1,014,365), which wasa continuation of U.S. patent application Ser. No. 13/487,927 filed onJun. 4, 2012, now U.S. Pat. No. 9,066,813, which claims the benefit ofU.S. Provisional Application No. 61/493,239, filed on Jun. 3, 2011. Theentire disclosures of each of the above applications are incorporatedherein by reference.

FIELD

The present invention relates generally to general surgery, orthopaedicand neurosurgical implants used for insertion within a space betweenhard tissue structures, and more specifically, but not exclusively,concerns devices implanted between bones to replace a resected,fractured or diseased structures and to maintain or reestablish properspacing between two bones.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Damage or disease that affects the integral structure of a bone or otherstructures, may lead to neurologic impairment or loss of structuralsupport integrity with possible permanent damage to the surrounding softtissue and adjacent neurologic, vascular and systemic structures.Maintaining or reestablishing anatomic spacing within a bone structureor other structural tissue is critical to ensuring continuedfunctionality and mobility of the patient and avoidance of long-termserious neurological, vascular or other systemic impairments. Pleasenote that the terms “implant” and “device” may be used interchangeablyand have the same meaning herein.

SUMMARY

According to one aspect, the present disclosure provides an interbodyfusion device. The interbody fusion device may include a top member, abase member, and an expansion member. The top member may include a firstbone-engaging side and a threaded opening. The base member may bereceived by the top member and may include a second bone-engaging sideand an open cavity aligned with the threaded opening of the top member.The expansion member may be disposed within the open cavity for rotationabout an axis. The expansion member may include a threaded portionthreadably engaged with the threaded opening. Rotation of the expansionmember may translate the first bone-engaging side away from the secondbone-engaging side along the axis.

According to another aspect, an interbody fusion device is provided. Theinterbody fusion device may include a top member, a base member, and anexpansion member. The top member may include a first bone-engaging sideand a threaded opening. The base member may be received by the topmember and may include a second bone-engaging side and an open cavity incommunication with the threaded opening of the top member. The expansionmember may be secured within the open cavity for rotation about an axisextending transverse to the first and second bone-engaging sides. Theexpansion member may include a threaded portion threadably engaged withthe threaded opening. Rotation of the expansion member may translate thetop member relative to the base member along the axis.

According to yet another aspect of the present disclosure, a surgicalmethod for maintaining a space between two vertebral bodies in a spinewith an interbody fusion device having a top member, a base member, andan expansion member is provided. The method may include inserting theinterbody fusion device into a space between the two vertebral bodies.The method may also include rotating the expansion member about a firstaxis extending transverse to a first bone-engaging side of the topmember and transverse to a second bone-engaging side of the base member.The method may further include threadably engaging the expansion memberwith a threaded opening of the top member. The method may also includetranslating the first bone-engaging side away from the secondbone-engaging side along the first axis.

Further, additional features and advantages are realized through thetechniques of the present invention. Other embodiments and aspects ofthe invention are described in detail herein and are considered a partof the claimed invention.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective view of one embodiment of a unidirectional,horizontal expandable interbody fusion device, in accordance with anaspect of the present invention;

FIG. 2 is a superior view of the expandable interbody fusion device ofFIG. 1 with the moveable member retracted, in accordance with an aspectof the present invention;

FIG. 3 is a superior view of the expandable interbody fusion device ofFIG. 1 with the moveable member extended, in accordance with an aspectof the present invention;

FIG. 4A shows a posterior view of the expandable interbody fusion deviceof FIG. 1 with the moveable member extended, in accordance with anaspect of the present invention;

FIG. 4B shows a lateral view of the expandable interbody fusion deviceof FIG. 1 with the moveable member extended, in accordance with anaspect of the present invention;

FIG. 4C shows a perspective view of the expandable interbody fusiondevice of FIG. 1 with the moveable member extended, in accordance withan aspect of the present invention;

FIG. 5 is a cross-sectional transverse plane, elevational view of oneembodiment of the expandable interbody fusion device of FIG. 1 takenalong line 5-5 in FIG. 4A, in accordance with an aspect of the presentinvention;

FIG. 6 is an enlarged cross-sectional sagittal plane, elevational viewof the expansion/retraction mechanism of the expandable interbody fusiondevice of FIG. 1 taken along line 6-6 in FIG. 4A, in accordance with anaspect of the present invention;

FIG. 7 is a perspective view of one embodiment of a unidirectional,vertical expandable interbody fusion device with the moveable memberretracted, in accordance with an aspect of the present invention;

FIG. 8 is a perspective view of the expandable interbody fusion deviceof FIG. 7 with the vertical moveable member extended, in accordance withan aspect of the present invention;

FIG. 9 is an enlarged, width-wise cross-sectional, elevational view ofone embodiment of the expandable interbody fusion device of FIG. 7showing the expansion/retraction mechanism taken along line 9-9 in FIG.11B, in accordance with an aspect of the present invention;

FIG. 10 is an enlarged, lateral cross-sectional, elevational view of theexpansion/retraction mechanism of the expandable interbody fusion deviceof FIG. 7 taken along line 10-10 in FIG. 11B, in accordance with anaspect of the present invention;

FIG. 11A shows a perspective view of the vertical, expandable interbodyfusion device of FIG. 7 with the moveable member extended, in accordancewith an aspect of the present invention;

FIG. 11B shows a superior view of the vertical, expandable interbodyfusion device of FIG. 7 with the moveable member extended, in accordancewith an aspect of the present invention;

FIG. 12 is a side, elevational view of the expandable interbody fusiondevice of FIG. 7, showing the tool insertion hole, in accordance with anaspect of the present invention;

FIG. 13 is a sectional view of the expandable interbody fusion device ofFIG. 7 taken along line 13-13 in FIG. 11B, along the plane of the toolinsertion hole, in accordance with an aspect of the present invention;

FIG. 14 is a perspective view of another embodiment of a unidirectional,horizontal expandable interbody fusion device, in accordance with anaspect of the present invention;

FIG. 15 is a superior view of the expandable interbody fusion device ofFIG. 14 with the moveable member extended and the tool inserted into atool insertion hole, in accordance with an aspect of the presentinvention;

FIG. 16 is an exploded view of the expandable interbody fusion device ofFIG. 14, in accordance with an aspect of the present invention;

FIG. 17 is a superior view of the expandable interbody fusion device ofFIG. 14, in accordance with an aspect of the present invention;

FIG. 18 is a cross-sectional transverse plane, elevational view of oneembodiment of the expandable interbody fusion device of FIG. 14 takenalong line 18-18 in FIG. 17, in accordance with an aspect of the presentinvention;

FIG. 19 is an enlarged cross-sectional sagittal plane, elevational viewof the expansion/retraction mechanism of the expandable interbody fusiondevice of FIG. 14 taken along line 19-19 in FIG. 17, in accordance withan aspect of the present invention; and

FIG. 20 is a perspective view of the embodiment of the expandableinterbody fusion device of FIG. 14, in accordance with an aspect of thepresent invention.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Generally stated, disclosed herein is an interbody fusion device orinterbody device that typically includes a body/base member, a threadedrod member, a support means, and a retractable member. The retractablemember extending either in a horizontal direction or a verticaldirection. As used herein, the terms “interbody fusion device,”“device,” “interbody device,” and “implant” may be used interchangeableas they essentially describe the same type of device. Further, acorresponding expansion tool used for expansion and contraction of theinterbody device is discussed. Finally, described herein is a surgicalmethod for using the interbody fusion device to maintain a space betweentwo vertebral bodies within a patient suffering from a diseased ordamaged disc or spinal column.

As depicted in FIG. 1, the general arrangement of a unidirectionalhorizontal expandable interbody fusion device 100, in accordance with anaspect of the present invention, includes a body member 110 and one sidemember 120. Also shown in FIG. 7 is the general arrangement of aunidirectional vertical expandable interbody fusion device 200, inaccordance with an aspect of the present invention that, includes a basemember 210 and one superior member 220. Shown in FIG. 14 is a secondgeneral arrangement of a unidirectional horizontal expandable interbodyfusion device 400, in accordance with an aspect of the present inventionthat, includes a base member 410 and one side member 420. In thisdetailed description and the following claims, the words proximal,distal, anterior, posterior, medial, lateral, superior and inferior aredefined by their standard usage for indicating a particular part of abone or implant according to the relative disposition of the naturalbone or directional terms of reference. For example, “proximal” meansthe portion of an implant nearest the torso, while “distal” indicatesthe portion of the implant farthest from the torso. As for directionalterms, “anterior” is a direction towards the front side of the body,“posterior” means a direction towards the back side of the body,“medial” means towards the midline of the body, “lateral” is a directiontowards the sides or away from the midline of the body, “superior” meansa direction above and “inferior” means a direction below another objector structure.

It is shown in FIG. 1, a first example of the unidirectional, horizontalexpandable interbody fusion device 100. The device 100 as seen in FIGS.1 and 2 has a generally rectangular geometry with various configuredlong sides to facilitate insertion and bone coverage. For examplepurposes, the long sides are arcuate although it is contemplated thatother geometrical shapes may also be used in the construct. The implant100 may likely include at least one moveable side member 120 and a bodymember 110. The side member 120 may be detachably coupled to the bodymember 110.

As seen in FIGS. 1, 2, 3 and 4A-C, body member 110 typically has atleast two oval shaped through holes 111 for insertion of bone graftmaterial disposed on the inferior and superior bone contacting surfaces105. The holes extend through these top and bottom surfaces 105 of thebody member 110. These openings 111 typically extend through both bonecontacting surfaces 105 and into the inner cavity of the body member110. The size and configuration of the openings 111 allow the surgeon toplace bone graft material inside the implant 100 to achieve a continuousfusion between the inferior and superior vertebral bodies.

As seen in FIG. 4A-C, side member 120 also may have polygonal shapedholes oriented in a horizontal direction. These holes may be encircledby a wall 114 projecting from an inner surface of side member 120 tofacilitate the orientation of the side member 120 when it translatesfrom a retracted to an expanded position and vice-a-versa. The wall 114may also include a horizontal slot 113 though which a stop pin 112 orother mechanism extends to keep the side member from overextending andbecoming disengaged with the body member.

Again as shown in FIG. 4A-C, positioned intermediate the oval holes is ameans for moving the side member 120. For example purposes, the meansfor moving the side member may include a threaded circular hole 122positioned within the side member 120 (also seen in FIG. 1). As shown insectional views depicted in FIGS. 5 and 6, threaded hole 122 isconfigured to threadingly engage with threaded rod member 123. Rotationof threaded rod member 123 will cause side member 120 to move either inan inward or outward direction relative to the body member 110. Theoverall width of the implant 100 can be changed via the rotation of thethreaded rod member 123 and the corresponding unidirectional movement ofside member 120. It is contemplated that other means for causing thecontrolled translation of side member 120 to occur may include aratcheting or locking sliding mechanism.

Also shown in FIGS. 1, 2, 3, and 4A-C are the superior and inferior bonecontacting surfaces 105. For example purposes, bone contacting surfaces105 are shown having teeth-like or tine structures projecting away fromthe superior and inferior surfaces. Although not shown, it is understoodby one skilled in the art that modular bone contacting surfaces, caps orplates may be used to provide for varying types of bone contactingsurfaces and structures, including, but not limited to sharp tines,porous coatings, biomaterial/ingrowth surfaces and ridge structures.Further, it is contemplated that angled bone contacting surfaces, capsor plates may be attachable to address various clinical deformities thatare encountered clinically. It is also understood that the bonecontacting surfaces 105 may be coated with bioactive or bone ingrowthcoatings.

As shown in FIGS. 1 and 4A-C, body member 110 has a generallyrectangular shape with three through openings passing along thetransverse plane. The holes are configured to receive the abovediscussed walls 114 of the side member 120 as the side member 120 ismoved relative to body member 110. The holes are generally positioned inthe lateral aspect of body member 110. A centralized through hole 122that for this embodiment is positioned between the above describedhorizontal holes is sized to receive the threaded rod member 123 orother means for moving the side member.

As shown in the sectional views of FIGS. 5 and 6, the threaded rodmember 123 will rotate within the body member 110 while engaging thethreaded hole 122 of the side member 120 causing movement thereof. Thesectional views of FIGS. 5 and 6 show the threaded rod 123 positionedwithin the central cavity of body member 110. A support ring 125 acts tocouple the threaded rod 123 to maintain the static position of theexpansion/retraction mechanism when rotated. Support ring 125 may be asnap ring or other similar type of structure that will nest within anotch 126 or other retainment mode within the inner cavity of the bodymember 110.

As discussed above and shown in FIG. 1, a stop pin 112 may be used toextend through each of the walls 114 in a medial direction and would besized to extend into the slot 113 of wall 114 of the side member 120.For example purposes, stop pin 112 is shown as being cylindricalalthough other shaped stops can be utilized.

Shown in FIG. 7, is an example of the unidirectional vertical expandableinterbody fusion device 200. The device 200 as shown in FIGS. 7, 8 and11A-B has a generally curved or banana shaped geometry. For examplepurposes, as seen in FIG. 11A-B, the long sides are arcuate although itis contemplated that other geometrical shapes may also be used in theconstruct, with the end portions being shown as comprised of smallerradiused portions to facilitate insertion and bone coverage. The implant200 may likely include at least one superior (although the moveablemember could be repositioned on the inferior aspect as well) moveablemember 220 and a base member 210. The superior or top member 220 may bedetachably coupled to the base member 210.

As seen in FIGS. 8, 11A-B, and 13, implant 200 typically has at leasttwo oval shaped through holes 201 for insertion of bone graft materialdisposed on the inferior and superior bone contacting surfaces 205. Forexample purposes, FIG. 11A-B shows implant 200 having four holes 201,although, more or less number of holes may be used depending on theclinical situation. These openings typically extend through both bonecontacting surfaces 205 and into the inner cavity of the base member210. The size and configuration of the openings 201 allow the surgeon toplace bone graft material inside the inner cavity of the implant 200 toachieve a continuous fusion between the inferior and superior vertebralbodies.

As seen in FIGS. 9, 10, and 13, top member 220 also may have at leastone opening 211 oriented in a vertical direction. Openings 211 areconfigured to facilitate the orientation of the top member 220 as ittranslates from a retracted to an expanded position and while alsokeeping it rotationally stationary. The openings 211 may also include amechanism which may be in the form of a stop pin, flange, lip or othermechanism that keeps the top member 220 from overextending anddisengaging from the base member 210.

Again as shown in FIGS. 7, 8, and 13, positioned intermediate the holes201 is a central through circular hole 222. Housed within hole 222 is ameans for extension and retraction of the top member 250. As shown insectional views depicted in FIGS. 9, 10, and 13, hole 222 may include anon-threaded portion and a threaded portion 223. Positioning of thethreaded portion 223 and the non-threaded portions may change dependingon the orientation of the implant 200, but generally threaded portion223 will be located within top member 220. Rotation of the means forextension and retraction 250 will cause top member 220 to move either ina superior or inferior direction relative to the base member 210. Theoverall height of the implant 200 can be changed via the rotation of themeans for extension and refraction 250 and the correspondingunidirectional movement of top member 220. It is contemplated that othermeans for extension and retraction of top member 220 may include aratcheting or locking sliding mechanism.

Also shown in FIGS. 7, 8, and 11A-B are the superior and inferior bonecontacting surfaces 205. For example purposes, bone contacting surfaces205 are shown having teeth-like or similar configured structuresprojecting away from the superior and inferior surfaces. Although notshown, it is understood by one skilled in the art that modular bonecontacting surfaces, caps or plates may be used to provide for varyingtypes of bone contacting surfaces and structures, including, but notlimited to sharp tines, porous coatings, biomaterial/ingrowth surfacesand ridge structures. Further, it is contemplated that angled bonecontacting surfaces, caps or plates may be attachable to address variousdeformities that are encountered clinically. It is also understood thatthe bone contacting surfaces 205 may be coated with bioactive or boneingrowth coatings.

FIGS. 9, 10, and 13 show the means for extension and contraction of thetop member 250 (or also known as the extension/contraction means orextension-retraction means) used in the device 200. Theextension/contraction means 250 includes a gear 251, a partiallythreaded rod member 252 and a retaining ring structure 253. Thesectional views of FIGS. 9, 10, and 13 show the extension/contractionmeans 250 positioned within a central or open cavity of base member 210and oriented in an vertical direction. As depicted, the plane of thegear 251 lies perpendicular to the longitudinal axis of the threaded rodmember 252. Therefore, when the gear 251 is rotated, the threaded rodmember 252 will turn and cause the engaged top member 210 to translateeither in a superior or inferior direction relative to the base member.Typically, the gear 251 is fixed proximate to one of the ends of thethreaded rod member 252 with the ring structure 253 generally positioneda distance from the gear 251, although still in the central region ofthe threaded rod member 252. The extension/contraction means 250functions to convert rotational movement of the gear 251 totranslational movement of the top member 220. The threaded rod member252 will typically have one threaded portion 254 that engages threadedportion 223 of hole 222 passing through top member 220.

As seen in FIGS. 9, 10, and 13, ring 253 acts to couple theextension/contraction means 250 and maintain the superior and inferiorposition of the mechanism when rotated. Ring 253 may be a snap ring orother similar type of structure that will nest within a notch 255 orother retainment mode within the inner cavity of the base member 210.

Although not shown, the teeth or cogs of gear 251 are sized to mate witha corresponding toothed end of an extension tool. The end of such a toolwould usually be inserted into hole 300 (see FIGS. 8, 12, and 13) andthen engage gear 251 when the gear teeth mesh with the tool end.Rotation of the tool by the user will cause gear 251 to rotate causingtop member 220 to translate as it moves along the threaded portion 223of the threaded rod member 252.

Referring now to FIGS. 14-19, with particular reference to FIGS. 14-17,a second example of a unidirectional, horizontal expandable interbodyfusion device 400 is shown. The device 400 as seen in FIGS. 14-17 has agenerally rectangular geometry with various configured long sides tofacilitate insertion and bone coverage. For example purposes, the longsides are arcuate although it is contemplated that other geometricalshapes may also be used in the construct. The implant 400 may likelyinclude at least one moveable side member 420 and a body member 410. Theside member 420 may be detachably coupled to the body member 410.

As seen in FIGS. 14, 15, and 18, body member 410 typically has at leasttwo oval shaped through holes 411 for insertion of bone graft materialdisposed on the inferior and superior bone contacting surfaces 405. Theholes extend through these top and bottom surfaces 405 of the bodymember 410. These openings 411 typically extend through both bonecontacting surfaces 405 and into the inner cavity of the body member410. The size and configuration of the openings 411 allow the surgeon toplace bone graft material inside the implant 400 to achieve a continuousfusion between the inferior and superior vertebral bodies.

As seen in FIGS. 15, 18, and 20, side member 420 also may have at leastone channel 406 oriented in the horizontal direction. These channels 406are configured to facilitate the orientation of the side member 420 asit translates from a retracted to an expanded position and vice-a-versa.The implant 400 may also include a mechanism which may be in the form ofa screw, stop pin, flange, lip or other mechanism that keeps the sidemember 420 from overextending and disengaging from the base member 410.As illustrated in FIG. 16, the mechanism is a screw 408.

As shown in FIGS. 16, 18, and 19, the screw 408 may also be used as partof the mechanism for extension and retraction of the side member 420 andmay be threaded. A hole 422 may be positioned intermediate the holes 411in the body member 410. Housed within the hole 422 and the cavity 424 isa means for extension and retraction of the side member 420. The hole422 is configured to mate with a threaded cylindrical member 423. Thethreaded cylinder member 423 includes a threaded portion that isconfigured to threadingly engage with the screw 408. Rotation of thethreaded cylindrical member 423 will cause screw 408 to move either inan inward or outward direction relative to the body member 410 therebymoving side member 420 in an inward or outward direction with screw 408.It is also contemplated that the threaded cylindrical member 423 mayinclude both a threaded portion and non-threaded portion. In addition,side member 420 may include a cavity 424 positioned intermediate theholes 411 which is exposed when the side member 420 is extended. Theoverall width of the implant 400 can be changed via the rotation of thethreaded cylindrical member 423 and the corresponding unidirectionalmovement of the screw 408 which moves the side member 420. It iscontemplated that other means for causing the controlled translation ofside member 420 to occur may include a ratcheting or locking slidingmechanism.

Also shown in FIGS. 14-16 and 20 are the superior and inferior bonecontacting surfaces 405. For example purposes, bone contacting surfaces405 are shown having teeth-like or tine structures projecting away fromthe superior and inferior surfaces. Although not shown, it is understoodby one skilled in the art that modular bone contacting surfaces, caps orplates may be used to provide for varying types of bone contactingsurfaces and structures, including, but not limited to sharp tines,porous coatings, biomaterial/ingrowth surfaces and ridge structures.Further, it is contemplated that angled bone contacting surfaces, capsor plates may be attachable to address various clinical deformities thatare encountered clinically. It is also understood that the bonecontacting surfaces 405 may be coated with bioactive or bone ingrowthcoatings.

As shown in FIG. 16, body member 410 has a generally rectangular shapewith two protrusions 412 extending along the transverse plane. Theprotrusions 412 are configured to engage the above discussed channels406 of the side member 420 as the side member 420 is moved relative tobody member 410. The protrusions 412 are generally positioned in thelateral aspect of body member 410. A centralized hole 422 that for thisembodiment is positioned between the above described protrusions 412 issized to receive the threaded cylindrical member 423 or other means formoving the side member 420.

As shown in the sectional views of FIGS. 18 and 19, the threadedcylindrical member 423 includes a gear 450 to enable the threadedcylindrical member 423 to rotate within the body member 410 and engagethe screw 408 causing movement of the side member 420. The sectionalviews of FIGS. 18 and 19 also show the screw 408 positioned within thecentral cavity of threaded cylindrical member 423 which is in turnpositioned within the central cavity of hole 422 of body member 410. Thescrew 408 is removably secured in opening 414 in the cavity 424 of theside member 420 to maintain the static position of theexpansion/retraction mechanism when rotated.

As shown in FIGS. 16, 18, and 19, a tool 430 may be used to expand andretract the side member 420 from the body member 410. The tool 430extends through an opening 432 in the body member 410 which extends fromthe exterior of the body member 410 to the hole 422. The tool 430includes a toothed end 434 for mating with the gear 450. The gear 450has teeth or cogs which are sized to mate with the corresponding toothedend 434 of the tool 430. The toothed end 434 of the tool 430 may beinserted into opening 432 of the body member 410 and then engage gear450 when the gear teeth mesh with the toothed end 434. Rotation of thetool 430 at the handle 436 by a user will rotate the toothed end 434 ofthe tool 430 causing the gear 450 to rotate thereby rotating thethreaded cylindrical member 423. Rotation of the threaded cylindricalmember 423 causes screw 408 to translate in the threaded cylindricalmember 423 thereby moving the side member 420 along. The threadedcylinder member 423 and screw 408 function to convert rotationalmovement of the gear 450 by the tool 430 to translational movement ofthe side member 420.

The biocompatible materials used to fabricate the dynamic horizontalimplant 100, the dynamic vertical implant 200, and the second dynamichorizontal implant 400 could include a myriad of metals, polymers andcomposites. Examples of these include PEEK, titanium and stainlesssteel.

The example surgical method for using any of the interbody fusiondevices 100, 200, 400 is well known in the art, including theappropriate surgical exposure and dissection techniques. The methodincludes, obtaining the properly sized and configured device 100, 200,400 relative to the target vertebral end plates that will be opposingthe superior and inferior surfaces 105, 205, 405. An expansion orextension tool, such as 430, is then inserted into the hole 122, 300 oropening 432 of the device 100, 200, 400 to secure it for insertion intothe spine. For example purposes only, we shall describe herein thetechnique as used in the insertion between two vertebral bodies tomaintain the disc space there between. The device 100, 200, 400 isusually slid from a lateral or posterior-lateral direction into thetarget disc space.

Following positioning of the device 100, 200, 400 within the disc space,the extension/expansion/insertion tool is rotated causing either theside member 120, 420 or top member 220 to move away from the body orbase member 110, 210, 410 resulting in the overall width dimension orheight dimension of the device 100, 200, 400 to increase or decrease,depending upon the direction of the rotation of theextension/contraction means. The user will stop rotating theextension/expansion tool once optimum support is achieved relative tothe inferior and superior vertebral bodies for implant 100, the stoppins 112 are engaged by the side member 120 thus, restraining anyfurther translation of the side member 120.

The method may further include the step of detaching theextension/expansion tool from the body or base member 110, 210, 410 andremoving the instrument from inside the living body.

It should be understood by those skilled in the art that the surgicalmethod described herein may also include alternatively, using modularbone contacting plates or surfaces which have been coupled in somemanner to an alternative embodiment of the body or base member 110, 210,410 or side member 120, 420 or top member 210 to accommodate variousclinical deformities or bone growth coatings.

Although the example embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions and substitutions can be madewithout departing from its essence and therefore these are to beconsidered to be within the scope of the following claims.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A method of using an interbody fusion device,comprising: preparing a space between two adjacent vertebral bodies;obtaining an interbody fusion device, wherein the interbody fusiondevice comprises: a top member having a first bone-engaging surface anda threaded opening; a base member received by the top member, the basemember having a second bone-engaging surface and an open cavity alignedwith the threaded opening of the top member; an expansion memberdisposed within the open cavity for rotation about an axis, theexpansion member having a threaded portion configured to threadablyengage with the threaded opening and a central bore to maintain anopening through the threaded opening in the first bone-engaging surfacethrough the open cavity in the second bone-engaging surface; and asupport ring coupled to the base member within the open cavity, thesupport ring configured to retain the expansion member within the basemember in a fixed position along the axis relative to the secondbone-engaging surface; wherein the expansion member further comprises agear portion and a radially extending portion disposed between the gearportion and the threaded portion, the radially extending portiondisposed adjacent the support ring; and using an expansion tool to movethe top member in a direction relative to the base member, wherein thesupport ring is positioned in a notch inset into the base member tosecure the top member within the base member.
 2. The method of claim 1,wherein the gear portion includes a first side and a second side withthe first side having a plurality of gear teeth and the second sidebeing in contact with the base member.
 3. The method of claim 1, whereinthe gear portion includes a plurality of axially extending gear teeth.4. The method of claim 3, wherein the base member includes a toolinsertion opening in communication with the open cavity.
 5. The methodof claim 4, wherein the method further comprises: obtaining theexpansion tool, the expansion tool comprising a handle, a shaft having afirst end and a second end, wherein the first end is connected to thehandle and the second end is configured for engagement with theexpansion member.
 6. The method of claim 5, wherein the method furthercomprises: inserting the expansion tool into the tool insertion openingand engaging the second end of the expansion tool with the expansionmember.
 7. The method of claim 6, wherein using the expansion tool tomove the top member in a direction relative to the base membercomprises: rotating the expansion tool to move at least one of the firstbone-engaging surface or second bone-engaging surface.
 8. The method ofclaim 7, wherein the first bone-engaging surface includes at least onefirst through hole, and the second bone-engaging surface includes atleast one second through hole aligned with the at least one firstthrough hole.
 9. The method of claim 7, wherein using the expansion toolto move the top member in a direction relative to the base membercomprises: rotating the expansion member about a first axis extendingtransverse to the first bone-engaging surface and the secondbone-engaging surface; threadably engaging the expansion member with thethreaded opening of the top member; and translating the firstbone-engaging surface away from the second bone-engaging surface alongthe first axis to contact the two adjacent vertebral bodies.
 10. Themethod of claim 9, wherein the expansion tool is rotated about a secondaxis that is transverse to the first axis to rotate the expansionmember.
 11. The method of claim 1, wherein the method further comprises:inserting the interbody fusion device into the space.
 12. The method ofclaim 1, wherein the support ring is non-threaded.
 13. A surgical methodfor maintaining a space between two vertebral bodies in a spine, themethod comprising: obtaining a movable interbody implant, the implantcomprising: a top member having a superior bone-engaging side and athreaded opening; a base member configured to be received by the topmember, the base member having an expansion tool opening, an inferiorbone-engaging side and an open cavity in communication with the threadedopening of the top member and expansion tool opening; an expansionmember positioned within the open cavity for rotation about an axisextending transverse to the superior and inferior bone-engaging sides,the expansion member having a threaded portion threadably engaged withthe threaded opening and a central bore to maintain an opening throughthe threaded opening in the superior bone-engaging side through the opencavity in the inferior bone-engaging side, and a support ring coupled toa notch inset into the base member within the open cavity, the supportring configured to retain the expansion member within the base member ina fixed position along the axis relative to the inferior bone-engagingside, wherein rotation of the expansion member moves the top memberrelative to the base member along the axis, while the support ringmaintains the fixed position of the expansion member relative to theinferior bone-engaging side along the axis; inserting the movableinterbody implant into a space between two vertebral bodies.
 14. Thesurgical method of claim 13, wherein the method further comprises:expanding the movable interbody implant by rotating the expansion memberabout the axis until the superior bone-engaging side and inferiorbone-engaging side pressingly contact the two vertebral bodies.
 15. Asurgical method for maintaining a space between two bones, the methodcomprising: obtaining a movable surgical implant, the implantcomprising: a top member having a first bone-engaging side and athreaded opening; a base member received by the top member, the basemember having a second bone-engaging side and an open cavity incommunication with the threaded opening of the top member; an expansionmember secured within the open cavity for rotation about an axisextending transverse to the first and second bone-engaging sides, theexpansion member having a threaded portion threadably engaged with thethreaded opening and a central bore to maintain an opening through thethreaded opening in the first bone-engaging side through the open cavityin the second bone-engaging side, and a support ring fixed to the basemember within the open cavity, the support ring configured to secure theexpansion member within the base member in a fixed position along theaxis relative to the second bone-engaging side, wherein rotation of theexpansion member translates the top member relative to the base memberalong the axis; wherein the support ring is configured to be snappedinto a notch in the base member within the open cavity to retain theexpansion member within the base member; and wherein the expansionmember further comprises a first end opposite the threaded portion, anda radially extending portion disposed between the first end and thethreaded portion, the radially extending portion disposed adjacent thesupport ring; and using an expansion tool to move the top member in adirection relative to the base member.
 16. The surgical method of claim15, wherein using an expansion tool to move the top member in adirection relative to the base member comprises: inserting the movablesurgical implant into a space between two bones; and enlarging themovable surgical implant by rotating the expansion member about the axisuntil the first bone-engaging side and second bone-engaging sidepressingly contact the two bones.
 17. The method of claim 15, whereinthe support ring is non-threaded.